Effects of rapid versus slow accumulation of eight hours of sleep loss

The present study assessed alertness, memory, and performance following thr ee schedules of similar to8 hr of sleep loss (slow, intermediate, and rapid accumulation) in comparison to an 8-hr time in bed (TIB) sleep schedule. T welve healthy individuals aged 21-35 completed each of four conditions acco rding to a Latin Square design: no sleep loss (8-hr TIB for 4 nights; 2300- 0700), slow (6-hr TIB for 4 nights; 0100-0700), intermediate (4-hr TIB for 2 nights; 0300-0700), and rapid (0-hr TIB for 1 night) sleep loss. On each day, participants completed a multiple sleep latency test (MSLT), a probed- recall memory task, a psychomotor vigilance task, a divided attention task, and the Profile of Mood States. "Rapid" sleep loss produced significantly more impairment on tests of alertness, memory, and performance compared to the "slow" accumulation of a comparable amount of sleep loss. The impairing effects of sleep loss vary as a function of rate, suggesting the presence of a compensatory adaptive mechanism operating in conjunction with the accu mulation of a sleep debt.